3.2.3 Ensure secure ICMP redirects are not accepted

Information

Secure ICMP redirects are the same as ICMP redirects, except they come from gateways listed on the default gateway list. It is assumed that these gateways are known to your system, and that they are likely to be secure.

Rationale:

It is still possible for even known gateways to be compromised. Setting net.ipv4.conf.all.secure_redirects to 0 protects the system from routing table updates by possibly compromised known gateways.

Solution

Run the following command to set the active kernel parameters and persist the settings:

# apiclient apply <<EOF
[settings.kernel.sysctl]
"net.ipv4.conf.all.secure_redirects" = "0"
"net.ipv4.conf.default.secure_redirects" = "0"
EOF

Run the following command to flush the routing cache:

# sysctl -w net.ipv4.route.flush=1

See Also

https://workbench.cisecurity.org/benchmarks/6709

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND SERVICES ACQUISITION

References: 800-53|CM-1, 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv7|5.1

Plugin: Unix

Control ID: 21543769b4d6ee50be1940f9c5d89f6f15db4eb510fff573842c5c069ba6975c